Summary of work: Previous research in this Laboratory and elsewhere has shown that in American samples, mean levels of some personality traits decline while others increase during the decade of the 20s. To investigate the cross-cultural generalizability of this adult developmental sequence, the NEO-PI-R was translated into Korean, Croatian, Portuguese, German, and Italian, and data were collected from college students and adults. The same pattern of age differences was found in each culture and in both sexes, suggesting this may be a universal maturational phenomenon. That hypothesis was further tested using a different measure of personality, the California Psychological Inventory, in the BLSA and the People's Republic of China. Cross-sectional age correlations in both samples were consistent with the hypothesis that Neuroticism, Extraversion, and Openness decline with age, and that Agreeableness and Conscientiousness increase. Longitudinal research on personality, stress and coping will continue.